Functional Group Priorities - Online Tutor, Practice Problems & Exam Prep

When naming compounds with multiple functional groups, prioritize the highest-ranking functional group as the parent chain. The order of priority is: carboxylic acids, aldehydes, ketones, alcohols, amines, and ethers. Use specific prefixes for substituents: alkoxy for ethers, amino for amines, hydroxy for alcohols, and oxo for aldehydes or ketones. Remember the mnemonic "cool alligators keep all animals excited" to recall the order of functional groups. This systematic approach is essential for accurately identifying and naming complex organic compounds.

Functional Group Priorities Concept 1

Now when it comes to naming compounds with multiple functional groups, we're going to say that priorities must be considered. And we're going to say that the functional group with the highest priority is named as the parent chain, and all other functional groups will be named as substituents. When it comes to functional group priorities, this is the order that you need to keep in mind. So carboxylic acids reign supreme. They have the highest priority of all the functional groups, followed by aldehydes, then ketones, then alcohols, then amines, and then ethers. These are the functional groups that we've curated because they're the ones that are usually mixed together within a multifunctional group compound. Now the memory tool we can use here is that cool alligators keep all animals excited. So this will help us remember cool for carboxylic acids, alligators for aldehydes, keep for ketones, all for alcohols, animals for amines, and then excited for ethers. Right. So just remember, the highest priority functional group forms the end of the name as the parent chain. All other functional groups will be substituents.

Functional Group Priorities Example 1

Here it says to provide parent chain names for each compound. In A, we have two functional groups present. We have an amine here and then we have an alcohol. Remember, the priority when it comes to functional groups has alcohols having higher priority than amines. Because of that, the parent chain is the one that's going to include the alcohol. And if we just name the alcohol within a vacuum, meaning we're not paying attention to the amine portion, what would the alcohol chain be called? Well, we'd start numbering from the end closest to the OH, so 1, 2, 3, 4, 5, 6, 7. The alcohol is on carbon number 1, so that'd be 1, and then 7 carbons is hept, and then it's an alcohol, so heptanol.

For the next one, we have a carboxylic acid group here and then we have a ketone group here. Remember, carboxylic acids reign supreme. They are the highest priority functional group. So, we're going to pay attention to that. So, if we're just looking at the carboxylic acid part and ignoring the ketone because we're just concerned with the parent chain, what would it be called? So we would say it'd be 1, 2, 3, 4. Four carbons here would be butanoic acid. Now we have a methyl group attached, we have a ketone attached. They also be incorporated into the name as well. But for right now, we're just concerned with what the parent chain would be. So again, remember, the highest priority functional group forms the parent chain name. Everything else will be a substituent.

Substituent Prefixes Concept 2

Now we're going to say if a functional group is named as a substituent, then it must use the prefixes listed below. So let's say that we have an ether portion that is a substituent. It'll be called an alkoxy group. Now, what do I mean by that? Well, let's say that the ether portion was an OCH₃. CH₃ is methyl, but because of the oxygen present, it would become methoxy. If we had an ethyl group attached to the oxygen, it's no longer ethyl; it's ethoxy. So that's what we mean by an alkoxy. Next, if we had an amine group, it'd be called amino as a substituent. And alcohol as a substituent is called hydroxy. And then finally, if we had an aldehyde or ketone as a substituent, they would be oxo. So keep these names in mind when each of these functional groups becomes a substituent.

Substituent Prefixes Example 2

So here it says provide the systematic name for the given molecule. Remember our memory tool. We're going to say here, "Cool alligators keep all animals excited." Here, that would mean that our ketone here would have higher priority than our alcohol. So our alcohol will be a substituent. Because the ketone has higher priority, we're going to start numbering from the end closer to it. So, we're going to say here 1, 2, 3, 4, 5, 6, 7, 8. Oh, when it's a substituent, it's called hydroxy. It's on carbon 7, so this would be 7-hydroxy. The ketone carbonyl is on carbon 3, so it would be 3. It is an 8 carbon chain, so it's octen, and then remember it's not octane anymore, since it's a ketone, we change the 'e' ending to -one, so it becomes octano. So the IUPAC name or systematic name of this structure would be 7-hydroxy-3-octanone.

Provide IUPAC name for following.

• A. 4-amino-3,3-dimethylpentanoic acid
• B. 4-amine-3-dimethylpentanoic acid
• C. 2-amino-3-dimethylpentaneoic acid
• D. 2-amine-3,3-dimethylpentanoic acid

Provide IUPAC name for following.

• A. 4-propoxypentanal
• B. 3-ethoxybutanal
• C. 2-ethoxypentanol
• D. 4-ethoxypentanal

Draw a structure for 7-oxoheptanoic acid.

• A.
• B.
• C.
• D.

Here’s what students ask on this topic:

What is the order of priority for functional groups in organic chemistry?

The order of priority for functional groups in organic chemistry is crucial for naming compounds with multiple functional groups. The priority order is as follows: carboxylic acids, aldehydes, ketones, alcohols, amines, and ethers. This means that carboxylic acids have the highest priority, followed by aldehydes, then ketones, alcohols, amines, and finally ethers. This order helps determine which functional group will be named as the parent chain and which will be named as substituents. A useful mnemonic to remember this order is 'cool alligators keep all animals excited,' where each word represents a functional group in the priority order.

How do you name a compound with multiple functional groups?

When naming a compound with multiple functional groups, you must prioritize the highest-ranking functional group as the parent chain. The functional group with the highest priority will determine the suffix of the compound's name. All other functional groups will be named as substituents using specific prefixes. For example, ethers are named as alkoxy groups, amines as amino groups, alcohols as hydroxy groups, and aldehydes or ketones as oxo groups. The order of priority is carboxylic acids, aldehydes, ketones, alcohols, amines, and ethers. This systematic approach ensures accurate and consistent naming of complex organic compounds.

What is the mnemonic to remember the order of functional group priorities?

The mnemonic to remember the order of functional group priorities is 'cool alligators keep all animals excited.' This mnemonic helps recall the priority order: carboxylic acids (cool), aldehydes (alligators), ketones (keep), alcohols (all), amines (animals), and ethers (excited). Using this mnemonic can make it easier to remember which functional group has the highest priority when naming compounds with multiple functional groups.

What prefixes are used for functional groups when they are substituents?

When functional groups are named as substituents, specific prefixes are used. For ethers, the prefix is 'alkoxy,' such as methoxy for OCH₃ or ethoxy for OCH₂CH₃. For amines, the prefix is 'amino.' For alcohols, the prefix is 'hydroxy.' For aldehydes and ketones, the prefix is 'oxo.' These prefixes help identify the functional groups when they are not the highest priority in the compound's name.

Why is it important to consider functional group priorities in organic chemistry?

Considering functional group priorities in organic chemistry is important because it ensures accurate and systematic naming of compounds with multiple functional groups. The highest priority functional group determines the parent chain and the suffix of the compound's name, while other functional groups are named as substituents with specific prefixes. This approach helps avoid confusion and maintains consistency in chemical nomenclature, making it easier to communicate and understand the structure and properties of complex organic compounds.